Implemented scheduled_executor

internal/platform/implementation/linux/scheduled_executor.cc

@@ -0,0 +1,82 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/platform/implementation/linux/scheduled_executor.h"
+
+#include <algorithm>
+#include <memory>
+#include <utility>
+
+#include "absl/time/time.h"
+#include "internal/platform/logging.h"
+
+namespace nearby {
+namespace linux {
+
+ScheduledExecutor::ScheduledExecutor()
+    : executor_(std::make_unique<nearby::linux::Executor>()),
+      shut_down_(false) {}
+
+// Cancelable is kept both in the executor context, and in the caller context.
+// We want Cancelable to live until both caller and executor are done with it.
+// Exclusive ownership model does not work for this case;
+// using std:shared_ptr<> instead of std::unique_ptr<>.
+std::shared_ptr<api::Cancelable> ScheduledExecutor::Schedule(
+    Runnable&& runnable, absl::Duration duration) {
+  if (shut_down_) {
+    NEARBY_LOGS(ERROR) << __func__
+                       << ": Attempt to Schedule on a shut down executor.";
+
+    return nullptr;
+  }
+
+  // Cleans completed tasks
+  std::remove_if(
+      scheduled_tasks_.begin(), scheduled_tasks_.end(),
+      [](std::shared_ptr<ScheduledTask>& task) { return task->IsDone(); });
+
+  std::shared_ptr<ScheduledTask> task =
+      std::make_shared<ScheduledTask>(std::move(runnable), duration);
+
+  scheduled_tasks_.push_back(task);
+  executor_->Execute([task]() { task->Start(); });
+  return task;
+}
+
+void ScheduledExecutor::Execute(Runnable&& runnable) {
+  if (shut_down_) {
+    NEARBY_LOGS(ERROR) << __func__
+                       << ": Attempt to Execute on a shut down executor.";
+    return;
+  }
+
+  executor_->Execute(std::move(runnable));
+}
+
+void ScheduledExecutor::Shutdown() {
+  if (!shut_down_) {
+    shut_down_ = true;
+    for (auto& task : scheduled_tasks_) {
+      task->Cancel();
+    }
+
+    scheduled_tasks_.clear();
+    executor_->Shutdown();
+    return;
+  }
+  NEARBY_LOGS(ERROR) << __func__
+                     << ": Attempt to Shutdown on a shut down executor.";
+}
+}  // namespace linux
+}  // namespace nearby

internal/platform/implementation/linux/scheduled_executor.h

@@ -0,0 +1,100 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef PLATFORM_IMPL_LINUX_SCHEDULED_EXECUTOR_H_
+#define PLATFORM_IMPL_LINUX_SCHEDULED_EXECUTOR_H_
+
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "absl/synchronization/notification.h"
+#include "absl/time/time.h"
+#include "internal/platform/implementation/cancelable.h"
+#include "internal/platform/implementation/scheduled_executor.h"
+#include "internal/platform/implementation/linux/executor.h"
+
+namespace nearby {
+namespace linux {
+
+#define TIMER_NAME_BUFFER_SIZE 64
+
+// An Executor that can schedule commands to run after a given delay, or to
+// execute periodically.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ScheduledExecutorService.html
+class ScheduledExecutor : public api::ScheduledExecutor {
+ public:
+  ScheduledExecutor();
+
+  ~ScheduledExecutor() override = default;
+
+  // Cancelable is kept both in the executor context, and in the caller context.
+  // We want Cancelable to live until both caller and executor are done with it.
+  // Exclusive ownership model does not work for this case;
+  // using std:shared_ptr<> instead if std::unique_ptr<>.
+  std::shared_ptr<api::Cancelable> Schedule(Runnable&& runnable,
+                                            absl::Duration duration) override;
+
+  // Executes the runnable task immedately.
+  void Execute(Runnable&& runnable) override;
+
+  // Shutdowns the executor, all scheduled task will be cancelled.
+  void Shutdown() override;
+
+ private:
+  class ScheduledTask : public api::Cancelable {
+   public:
+    explicit ScheduledTask(Runnable&& task, absl::Duration duration)
+        : task_(std::move(task)), duration_(duration) {}
+
+    bool Cancel() override {
+      if (is_executed_ || is_cancelled_) {
+        return false;
+      }
+
+      is_cancelled_ = true;
+      notification_.Notify();
+      return true;
+    };
+
+    void Start() {
+      if (is_executed_ ||
+          notification_.WaitForNotificationWithTimeout(duration_)) {
+        return;
+      }
+
+      is_executed_ = true;
+      task_();
+    }
+
+    bool IsDone() const { return is_cancelled_ || is_executed_; }
+
+   private:
+    Runnable task_;
+    absl::Duration duration_;
+    absl::Notification notification_;
+    bool is_cancelled_ = false;
+    bool is_executed_ = false;
+  };
+
+  std::unique_ptr<nearby::linux::Executor> executor_ = nullptr;
+  std::vector<std::shared_ptr<ScheduledTask>> scheduled_tasks_;
+  std::atomic_bool shut_down_ = false;
+};
+
+}  // namespace linux
+}  // namespace nearby
+
+#endif  // PLATFORM_IMPL_LINUX_SCHEDULED_EXECUTOR_H_